Figure 2
From: Contact geometry and mechanics predict friction forces during tactile surface exploration
Example patterns of finger-surface contact, extracted via high-speed video capture and analysis (see Methods), at three successive instants (A–C) for each of the six relief surfaces used in the study, exemplifying three different contact conditions. At initial finger contact (A) with the relief feature, the contact interface \({{\mathscr{C}}}_{1}\) of the finger with the flat region to the left of the relief feature is large, and (B) decreases as the finger traverses the inclined region, and becomes supported on the relief feature, where a second disconnected contact interface \({{\mathscr{C}}}_{2}\), develops. For the bump surfaces, this is followed by the development of a third disconnected contact region, \({{\mathscr{C}}}_{3}\), which forms as the finger descends a second slanted region.
